Electronic devices, such as cellular telephones, cameras, and computers, commonly use image sensors to capture images. A typical CMOS (complementary metal-oxide-semiconductor) imager circuit includes a focal plane array of pixels, and each pixel includes a photo-sensor, such as a photogate, or photodiode, for accumulating photo-generated charge in a portion of the substrate.
Many conventional high-performance image sensors are described by one or more specifications, such as high resolution, high dynamic range, high speed, high quantum efficiency, low noise, low dark current, no image lag, charge storage capacity, output voltage swing, etc. While some of the specifications are interrelated, some are trade-offs due to the physical properties and the design of the image sensor. For example, as the pixel size decreases, the amount of light that reaches the photosensor decreases, which may result in low quantum efficiency. Additionally, image sensors with pixels and/or circuits that are very close to each other may exhibit optical artifacts due to noise, charge migrating to adjacent photosensors, and/or cross-talk, which negatively impacts the image quality.